CCNP experiment: BGP routing black hole neighbor Full-mesh Solution

[Experimental environment] liehuo.net

C3640-IK9O3S-M Version 12.4 (10) liehuo.net

[Tutorial Objective] veryhuo.com

Uses Full-mesh to resolve BGP routing black hole liehuo.net

[Experiment topology] liehuo.net

Liehuo.net

[Experiment description] lie # fire # Network

BGP distribution. R2, R3, and R4 run the OSPF protocol. The objective is to enable 1.1.1.1 <-> 5.5.5.5 to access veryhuo.com from each other.

BGP neighbor relationship is established using the loopback interface. R1 <-> R2 <-> R4 <-> R5 liehuo.net

Create a default route between R1 <-> R2 and R4 <-> R5 to ensure the establishment of BGP neighbor relationship # fire # Network

Data Layer BGP routing black hole problem: R3 does not have 1.1.1.1 or 5.5.5 route entries, leading to the routing black hole veryhuo.com

Solution: Run BGP on R3 and establish a BGP neighbor relationship with R2 and R4. The routes 1.1.1.1 and 5.5.5 are learned through IBGP.

Lie-fire-network

Note: The BGP synchronization and Next Hop problems liehuo.net

[Tutorial] veryhuo.com

1. Basic configuration of R1, port, default route: Strong-fire-network

!
Interface Loopback0
Ip address 1.1.1.1 255.255.255.0
!
Interface Serial0/0
Ip address 12.0.0.1 255.255.255.0
Clock rate 64000
!
Ip route 2.2.2.2 255.255.255.255.255 12.0.0.2-fire-Net

2. Basic R2 configuration, port, default route, OSPF: veryhuo.com

!
Interface Loopback0
Ip address 2.2.2.2 255.255.255.0
!
Interface Serial0/0
Ip address 12.0.0.2 255.255.255.0
!
Interface Serial0/1
Ip address 23.0.0.1 255.255.255.0
Clock rate 64000
!
Router ospf 110
Router-id 2.2.2.2
Network 2.2.2.0 0.0.0.255 area 0
Network 23.0.0.1 0.0.0.0 area 0
!
Ip route 1.1.1.1 255.255.255.255 12.0.0.1 liehuo.net

3. basic configuration of R3, port, OSPF: strong # fire # Network

!
Interface Loopback0
Ip address 3.3.3.3 255.255.255.0
!
Interface Serial0/0
Ip address 34.0.0.1 255.255.255.0
Clock rate 64000
!
Interface Serial0/1
Ip address 23.0.0.2 255.255.255.0
!
Router ospf 110
Router-id 3.3.3.3
Network 3.3.3.0 0.0.0.255 area 0
Network 23.0.0.2 0.0.0.0 area 0
Network 34.0.0.1 0.0.0.0 area 0
! Veryhuo.com

4. basic configuration of R4, port, default route, OSPF: Strong Fire Network

!
Interface Loopback0
Ip address 4.4.4.4 255.255.255.0
!
Interface Serial0/0
Ip address 34.0.0.2 255.255.255.0
!
Interface Serial0/1
Ip address 45.0.0.1 255.255.255.0
Clock rate 64000
!
Router ospf 110
Router-id 4.4.4
Network 4.4.4.0 0.0.0.255 area 0
Network 34.0.0.2 0.0.0.0 area 0
!
Ip route 5.5.5.5 255.255.255.255 45.0.0.2

Liehuo.net

5. R5 basic configuration, port, default route: liehuo.net

!
Interface Loopback0
Ip address 5.5.5.5 255.255.255.0
!
Interface Serial0/1
Ip address 45.0.0.2 255.255.255.0
!
Ip route 4.4.4 255.255.255.255 45.0.0.1 liehuo.net

6. Configure EBGP between R1 and R2

// Configure AS 1 in R1
Router bgp 1
// Disable synchronization by default
No synchronization
// Set the bgp router-id
Bgp router-id 1.1.1.1
// Advertise route entries
Network 1.1.1.0 mask 255.255.255.0
// Set the neighbor AS number and use the loopback interface to establish a neighbor relationship. Change the default TTL value from 1 to 2.
Neighbor 2.2.2.2 remote-as 3
Neighbor 2.2.2.2 ebgp-multihop 2
Neighbor 2.2.2.2 update-source Loopback0
No auto-summary liehuo.net

// R2 configure AS 3
Router bgp 3
No synchronization
// Set the bgp router-id. It is recommended to be consistent with OSPF.
Bgp router-id 2.2.2.2
Neighbor 1.1.1.1 remote-as 1
Neighbor 1.1.1.1 ebgp-multihop 2
Neighbor 1.1.1.1 update-source Loopback0
No auto-summary
! Lie-fire-network

7. Configure the EBGP between R4 and R5.

// Configure AS 3 on R4
Router bgp 3
No synchronization
Neighbor 5.5.5 remote-as 5
Neighbor 5.5.5.5 ebgp-multihop 2
Neighbor 5.5.5.5 update-source Loopback0
No auto-summary strong # fire # Network

// R5 configure AS 5
Router bgp 5
No synchronization
Network 5.5.5.0 mask 255.255.255.255.0
Neighbor 4.4.4 remote-as 3
Neighbor 4.4.4 ebgp-multihop 2
Neighbor 4.4.4 update-source Loopback0
No auto-summary liehuo.net

8. Use Peer Group to simplify configuration, save memory, configure IBGP between R2, R3, and R4, and solve the problem of routing black hole through full interconnection of neighbors

// R2 establishes a neighbor relationship with R3 and R4.
Router bgp 3
Neighbor slyar peer-group
Neighbor slyar remote-as 3
Neighbor slyar update-source Loopback0
Neighbor slyar next-hop-self
Neighbor 3.3.3.3 peer-group slyar
Neighbor 4.4.4 peer-group slyar liehuo.net

// R3 establishes a neighbor relationship with R2 and R4
Router bgp 3
Neighbor slyar peer-group
Neighbor slyar remote-as 3
Neighbor slyar update-source Loopback0
Neighbor slyar next-hop-self
Neighbor 2.2.2.2 peer-group slyar
Neighbor 4.4.4 peer-group slyar liehuo.net

// R4 establishes a neighbor relationship with R2 and R3
Router bgp 3
Neighbor slyar peer-group
Neighbor slyar remote-as 3
Neighbor slyar update-source Loopback0
Neighbor slyar next-hop-self
Neighbor 2.2.2.2 peer-group slyar
Neighbor 3.3.3.3 peer-group slyar veryhuo.com

Because synchronization is disabled on all routers running IBGP and the next hop-self command is used to solve the next hop problem, the BGP entries on all routers are the best, in addition, you can perform normal forwarding through recursive routing queries. Liehuo.net

9. Check the route table's strong & fire & Network

R1 # sh ip ro
1.0.0.0/24 is subnetted, 1 subnets
C 1.1.1.0 is directly connected, Loopback0
2.0.0.0/32 is subnetted, 1 subnets
S 2.2.2.2 [1/0] via 12.0.0.2
5.0.0.0/24 is subnetted, 1 subnets
B 5.5.5.0 [20/0] via 2.2.2.2, 00:59:19
12.0.0.0/24 is subnetted, 1 subnets
C 12.0.0.0 is directly connected, Serial0/0 strong/fire/Network

R2 # sh ip ro
34.0.0.0/24 is subnetted, 1 subnets
O 34.0.0.0 [110/128] via 23.0.0.2, 01:04:19, Serial0/1
1.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
S 1.1.1.1/32 [1/0] via 12.0.0.1
B 1.1.1.0/24 [20/0] via 1.1.1.1, 01:13:12
2.0.0.0/24 is subnetted, 1 subnets
C 2.2.2.0 is directly connected, Loopback0
3.0.0.0/32 is subnetted, 1 subnets
O 3.3.3.3 [110/65] via 23.0.0.2, 01:04:19, Serial0/1
4.0.0.0/32 is subnetted, 1 subnets
O 4.4.4.4 [110/129] via 23.0.0.2, 01:04:21, Serial0/1
5.0.0.0/24 is subnetted, 1 subnets
B 5.5.5.0 [200/0] via 4.4.4.4, 01:02:00
23.0.0.0/24 is subnetted, 1 subnets
C 23.0.0.0 is directly connected, Serial0/1
12.0.0.0/24 is subnetted, 1 subnets strong # fire # Network
C 12.0.0.0 is directly connected, Serial0/0 veryhuo.com

R3 # sh ip ro
34.0.0.0/24 is subnetted, 1 subnets
C 34.0.0.0 is directly connected, Serial0/0
1.0.0.0/24 is subnetted, 1 subnets
B 1.1.1.0 [200/0] via 2.2.2.2, 01:02:46
2.0.0.0/32 is subnetted, 1 subnets
O 2.2.2.2 [110/65] via 23.0.0.1, 01:04:38, Serial0/1
3.0.0.0/24 is subnetted, 1 subnets
C 3.3.3.0 is directly connected, Loopback0
4.0.0.0/32 is subnetted, 1 subnets
O 4.4.4.4 [110/65] via 34.0.0.2, 01:04:38, Serial0/0
5.0.0.0/24 is subnetted, 1 subnets
B 5.5.5.0 [200/0] via 4.4.4.4, 01:02:26
23.0.0.0/24 is subnetted, 1 subnets
C 23.0.0.0 is directly connected, Serial0/1

Veryhuo.com

R4 # sh ip ro
34.0.0.0/24 is subnetted, 1 subnets
C 34.0.0.0 is directly connected, Serial0/0
1.0.0.0/24 is subnetted, 1 subnets
B 1.1.1.0 [200/0] via 2.2.2.2, 01:02:32
2.0.0.0/32 is subnetted, 1 subnets
O 2.2.2.2 [110/129] via 34.0.0.1, 01:04:54, Serial0/0
3.0.0.0/32 is subnetted, 1 subnets
O 3.3.3.3 [110/65] via 34.0.0.1, 01:04:54, Serial0/0
4.0.0.0/24 is subnetted, 1 subnets
C 4.4.4.0 is directly connected, Loopback0
5.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
S 5.5.5.5/32 [1/0] via 45.0.0.2
B 5.5.5.0/24 [20/0] via 5.5.5.5, 01:13:23
23.0.0.0/24 is subnetted, 1 subnets
O 23.0.0.0 [110/128] via 34.0.0.1, 01:04:56, Serial0/0
45.0.0.0/24 is subnetted, 1 subnets liehuo.net
C 45.0.0.0 is directly connected, Serial0/1 liehuo.net

R5 # sh ip ro
1.0.0.0/24 is subnetted, 1 subnets
B 1.1.1.0 [20/0] via 4.4.4.4, 01:02:48
4.0.0.0/32 is subnetted, 1 subnets
S 4.4.4.4 [1/0] via 45.0.0.1
5.0.0.0/24 is subnetted, 1 subnets
C 5.5.5.0 is directly connected, Loopback0
45.0.0.0/24 is subnetted, 1 subnets
C 45.0.0.0 is directly connected, Serial0/1 veryhuo.com

10. Verify that the loopback port 1.1.1.1 is used on R1 to connect to the v5.5.5 Network

R1 # ping 5.5.5 so 1.1.1.1
Sending 5, 100-byte ICMP Echos to 5.5.5.5, timeout is 2 seconds:
Packet sent with a source address of 1.1.1.1
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 76/92/108 MS veryhuo.com

11. rating liehuo.net

This method is obviously not available in the actual project: liehuo.net

Complicated configuration;

Fire Network

Need to maintain a large number of IBGP relationships # fire # Network

Consume a large amount of resources;

Liehuo.net

Other methods will be introduced later.